We propose a new intermediate band GaAs solar cell comprising an Al_xGa_1-xAs absorber with built-in GaSb type-II quantum dots (QDs) [a gradual Al_xGa_1-xAs absorber with built-in Al_yGa_1-ySb QDs (0<x=y<0.40) as a variant] separated from the depletion region. We study the modification of the band alignment at type-II interface by two-photon absorption of concentrated sunlight. Our calculation shows that photogenerated carriers produce localized exciton-like electron-hole pairs spatially separated at QDs. Local field of such pairs may essentially modify potential barrier surrounding QDs, increase recombination lifetime of mobile carriers and additional photocurrent generated by two photon absorption. Concentration of about 300-sun pushes by 15% up the conversion efficiency as compared to the efficiency of the reference single junction GaAs solar cell without QDs.

Date Published: 25 March 2013
PDF: 7 pages
Proc. SPIE 8620, Physics, Simulation, and Photonic Engineering of Photovoltaic Devices II, 86200K (25 March 2013); doi: 10.1117/12.2002455

Published in SPIE Proceedings Vol. 8620:
Physics, Simulation, and Photonic Engineering of Photovoltaic Devices II
Alexandre Freundlich; Jean-Francois Guillemoles, Editor(s)